Seven times a guest at the White House, choreographer Alwin Nikolais stood outside the north portico yesterday, a hefty sterling silver National Medal of Arts in a box under his arm, the noonday sun glimmering in his blue eyes, and an afternoon of firsts behind him.

"It was the first time I've sat at the president's table -- and with so few people," Nikolais said. "{Reagan} was magnificent! He was generous with his wit and his conversation. His stories were most engaging, and also, they were done in a very friendly, warm manner which is very endearing."

He already had a small red French Legion of Honor award pinned to his lapel, but Nikolais said of the arts medal, "This is the one I'm most proud of -- it is the first big U.S. government award I have received. This is only the third year of the award, so to be this early in receiving it -- well, it's very prestigious for me and I'm proud."

Nothing could diminish the occasion. Not even Nancy Reagan stumbling a bit over the pronunciation of his name earlier when she presented the award at a luncheon ceremony honoring Nikolais and 10 other winners of the third annual National Medals of the Arts.

Mrs. Reagan also had difficulty pronouncing the names of poet Howard Nemerov and sculptor Isamu Noguchi, and after floundering among the syllables of "philanthropist," she finally turned to her husband and said, "I seem to be having trouble with my words." Reagan smiled back at her and she proceeded.

Asked later why the first lady had trouble pronouncing her words, spokeswoman Wendy Weber said, "Everything's just fine ... I don't have an explanation."

Other honorees sitting with Nikolais and the president at lunch were singer Ella Fitzgerald, arts patron Sydney Lewis, Noguchi and Nemerov. Composer William Schuman, painter Romare Bearden, opera patron J. W. Fisher and Frances Lewis, the other half of the husband-and-wife art-collecting team from Charlottesville, Va., sat with Mrs. Reagan. Two of the winners were unable to attend: poet Robert Penn Warren, whose ill health prevented him from leaving his home in Fairfield, Conn., and arts patron Armand Hammer, who on Monday slipped in his bathroom and fractured a rib.

"The arts and humanities teach us who we are and what we can be," Reagan told the honorees, their families and other guests. "They're at the very core of the culture of which we are a part."

Noting that this year's awards coincide with the bicentennial of the Constitution, Reagan said, "We honor the arts not because we want monuments to our own civilization, but because we are a free people and the arts are among our finest creations and reflections of our life."

After the ceremony, when the guests spilled outside, Nikolais talked about another first: the opportunity to meet dancer Mikhail Baryshnikov, a luncheon guest. "You know, I had never met him personally before. So we met, quite enthusiastically each for the other."

Asked if Baryshnikov had ever danced in any of his productions, the choreographer laughed and said, "No, no, no. The most he's ever done, he's been to two performances of mine. So I said to him, I need five new dancers and if he's out of a job I'd be very happy to help him."

Nemerov and his wife Peggy delighted in the size of the medal. "Here, lift it up, you'll see," Peggy Nemerov urged a small group of reporters. "Listen, it weighs a ton!" Her husband, she said, is "going to open his shirt and wear {the medal} hanging down to his navel."

Nemerov, however, said that was not in his plans. "We're just going to sit in St. Louis and listen to our hair grow," he said.

Like a true poet, he drew upon the words of Samuel Johnson to describe lunching with the president: "It was not for me to bandy civilities with my sovereign." Translation: Reagan told the stories and the jokes; Nemerov listened and laughed.

Seated to Nemerov's left during the lunch was Fitzgerald. What, he was asked, did the jazz singer from Beverly Hills and the poet from St. Louis talk about? "Oh, we talked about what we could eat and what we usually ate -- the conversations of the great."

Fitzgerald found herself the nucleus of a cell full of bustling reporters. "I hope nobody falls," she said as she inched her way across the White House front lawn. "My shoes are too big, but they feel good."

Microphones clustered under her chin and questions flew at her, "How do you feel? ... How do you feel?"

"I'm just so thrilled today -- sitting next to the president," she answered. "This has been like a big celebration."

And two minutes later: "Can you tell us again, what does it feel like?"

A different answer: "Now I think I can eat. At lunch my stomach was going on."

The food that Fitzgerald had watched but barely ate? Chilled crab and sorrel soup; gruyere cheese bow ties; veal pa~te' printanier with a White House herb garden sauce; spaetzle salad with asparagus vinaigrette, and a raspberry and blueberry mousse cake.

Other guests at yesterday's luncheon included actress Celeste Holm, Chief Justice William Rehnquist, Sen. Mark Hatfield, U.S. Information Agency Director Charles Wick, National Gallery of Art Director J. Carter Brown, artist Helen Frankenthaler, choreographer Martha Graham, newscaster Roger Mudd and Sen. Edward Kennedy.